Tellurium in Organic Synthesis

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Abbreviations 
AIBN 
CTAB 
DIBAL-H 
DME 
DMSO 
ee 
ESR 
GC-MS 
HMPA 
LICA 
LiTMP 
m-CPBA 
MPLC 
NBSP 
NMP 
NOESY 
PTC 
TBTH 
TCNQ 
TEMPO 
TFA 
TLC 
TMEDA 
TUDO 
2,2'-Azo bisisobutyronitrile 
Cetyl trimethylammonium bromide 
Diisobutylaluminium hydride 
1,2-Dimethoxyethane 
Dimethyl sulfoxide 
Enantiomeric excess 
Electron spin resonance 
Gas chromatography-mass spectrum 
Hexamethylphosphoric acid triamide 
Lithium isopropylcyclohexylamide 
Lithium 2,2,6,6-tetramethylpiperidide 
meta-Chloroperbenzoic acid 
Medium pressure liquid chromatography 
para-Nitrobenzenesulphonyl peroxide 
N-methyl-2-pyrrolidinone 
Nuclear overhauser enhancement spectroscopy 
Phase transfer catalyst 
Tributyltin hydride 
7,7,8,8-Tetracy ano-pa ra-quinodimethane 
2,2,6,6-Tetramethyl-l-piperidinyloxy free radical 
Trifluoroacetic acid 
Thin layer chromatography 
N,N,N',N'-tetramethyl- 1,2-ethanediamine 
Thiourea dioxide 
XXV 
– 1 –
Introduction
1.1 SOME PHYSICAL PROPERTIES OF TELLURIUM
The Pauling electronegativities of carbon and tellurium are, respectively, 2.5 and 2.1. This,
in addition to the large volume of the tellurium atom (atomic radius 1.37, ionic radius
2.21), promotes easy polarization of Te–C bonds. The ionic character of the bonds
increases in the order C(sp3)!Te"C(sp2)!Te"C(sp)!Te, in accordance with the elec-
tronegativity of carbon accompanying the s character (Table 1.1).
The Te!C bond therefore exhibits a high reactivity, as demonstrated typically by the
easy heterolytic cleavage towards nucleophilic reagents.
1.2 RELEVANT MONOGRAPHS AND REVIEW ARTICLES
1. Rheinboldt, H. in Houben-Weyl-Methoden der Organischen Chemie (ed. E. Muller). 4th edn,
Vol. IX. Georg Thieme, Stuttgart, 1955.
2. Petragnani, N.; Moura Campos, M. Organomet. Chem. Rev. 1967, 2, 61.
3. Cooper, W. C. (ed.). Tellurium. Van Nostrand Rheinhold, New York, 1971.
4. Irgolic, K. J.; Zingaro, R. in Organometallic Reactions (eds. E. Becker; M. Tsutsui). Wiley, New
York, 1971.
5. Irgolic, K. J. The Organic Chemistry of Tellurium. Gordon and Breach, New York, 1974.
6. Irgolic, K. J. J. Organomet. Chem. 1975, 103, 91. lrgolic, K. J. J. Organomet. Chem. 1977, 130,
411. Irgolic, K. J. J. Organomet. Chem. 1978, 158, 235; Irgolic, K. J. J. Organomet. Chem.
1980, 189, 65. Irgolic, K. J. J. Organomet. Chem. 1980, 203, 368.
1
Table 1.1
Some physical properties of the VIA family of elements
Element Atomic Atomic Electronic Pauling Ionization Ionic Atomic
number mass configuration electronegativity potential radius radius
O 8 15.99 1s22s22p4 3.5 13.61 1.40 0.66
S 16 32.06 2s22p63s23p4 2.5 10.36 1.84 1.04
Se 34 78.96 3s23p63d104s24p4 2.4 9.75 1.98 1.17
Te 52 127.6 4s24p64d105s25p4 2.1 9.01 2.21 1.37
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2 1. INTRODUCTION
7. Uemura, S. Nippon Kagaku Kaishi 1981, 36, 381.
8. Petragnani, N.; Comasseto, J. V. Proceedings of the 4th International Conference of the Organic
Chemistry of Selenium and Tellurium (eds. F. Y. Berry; W. R. McWhinnie), pp. 98–241. The
University of Aston in Birmingham, Birmingham, 1983.
9. Uemura, S. J. Synth. Org. Chem. Jpn. 1983, 41, 804.
10. Engman, L. Acc. Chem. Res. 1985, 18, 274.
11. Petragnani, N.; Comasseto, J. V. Synthesis 1986, 1.
12. Suzuki, H. Synth. Org. Chem. Jpn. 1987, 45, 603.
13. Sadekov, D.; Rivkin, B. B.; Minkin, V. Y. Russ. Chem. Rev. 1987, 56, 343.
14. Patai, S.; Rappoport, Z. (ed.). The Chemistry of Organic Selenium and Tellurium Compounds,
Vols I and II. Wiley, New York, 1986, 1987.
15. Engman, L. Phosphorus Sulfur 1988, 38, 105.
16. Irgolic, K. Y. Houben-Weyl Methods of Organic Chemistry (ed. D. Klamann). 4th edn, Vol. E12b.
Georg Thieme, Stuttgart, 1990.
17. Petragnani, N.; Comasseto, J. V. Synthesis 1991, 793.
18. Petragnani, N.; Comasseto, J. V. Synthesis 1991, 897.
19. Petragnani, N. Tellurium in Comprehensive Organometallic Chemistry II (ed. A. McKillop). 
Vol. 11, Chapter 14. Pergamon, Elsevier, 1995.
20. Comasseto, J. V.; Lo, W. L.; Petragnani, N.; Stefani, H. A. Synthesis 1997, 4, 373.
21. Petragnani, N.; Stefani, H. A. Tetrahedron 2005, 61, 1613.
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– 2 –
Preparation of the More Important
Inorganic Tellurium Reagents
2.1 TELLURIUM TETRACHLORIDE
Tellurium tetrachloride is prepared directly from the respective elements.1
Experimental procedure1. The apparatus in Figure 2.1 is charged with 100–150 g of fine-
powdered Te (the apparatus and the Te have been previously heated overnight at 110°C to
ensure dryness). A stream of Cl2 (dried by bubbling in concentrated H2SO4) is slowly intro-
duced by means of a Tygon tube; meanwhile, the apparatus is heated with a small burner
flame. After a few minutes the solid Te begins to be converted into a black liquid. The reac-
tion is exothermic (and proceeds spontaneously), but the absorption of Cl2 is accelerated
by heating the mixture from time to time. After a while the mixture becomes clearer,
giving finally an amber-coloured liquid, which by increased heating forms a vapour of the
Te + 2Cl2 TeCl4
Figure 2.1 Apparatus to prepare TeCl4.
3
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4 2. PREPARATION OF THE MORE IMPORTANT INORGANIC TELLURIUM REAGENTS
same colour. At that time the absorption is complete and all the Te has been converted into
TeCl4. By vigorous burner heating, the product is transferred by distillation, under a con-
tinuous Cl2 stream, into the tubes, where it solidifies. The tubes are detached from the
apparatus by melting. The yield is 90%.
Tellurium tetrachloride is a pale yellow crystalline solid, melting point (m.p.) 225°C,
highly hygroscopic, soluble in dioxane, acetone, ether, methanol and ethanol but less sol-
uble in benzene and chloroform.
Tellurium tetrachloride is instantaneously hydrolysed by water, giving tellurium
oxochloride, which is soluble in concentrated hydrochloric acid, forming HTeCl5 and
H2TeCl6.
The Raman data suggest the ionic structure for TeCl3! Cl" in both the solid and liquid
states.2
2.2 TELLURIUM DIOXIDE
Tellurium dioxide is prepared by oxidation of elemental tellurium with concentrated nitric
acid.3
Experimental procedure.3 Commercial Te (20 g, finer than 60 mesh) is weighed into a
1000 mL beaker, covered with H2O (200 mL) and treated by the slow addition of 95 mL
of concentrated HNO3 (95 mL, specific gravity 1.42). The reaction is allowed to continue
for 5–10 min with occasional agitation. Insoluble impurities are removed immediately by
filtration on a Büchner funnel. The filtrate is transferred to a 600 mL beaker. Concentrated
HNO3 (65 mL) is then added and the solution boiled until oxides of nitrogen have been
expelled. Basic nitrates of antimony and bismuth precipitate at this point if these sub-
stances are present as impurities. These are removed by filtering through asbestos, after
which the clear liquor is evaporated gently on a water bath under a hood in an open 600
mL beaker. Basic tellurium nitrate is deposited. The evaporation is continued until the
solution volume has been reduced to 100 mL. The solution is then cooled. The crystalline
deposit is filtered, washed with H2O on a suction filter and air dried. The dry crystals are
placed in a 400 mL beaker, covered by inverting a 1000 mL beaker over the smaller beaker,
and heated at a hot-plate temperature of 400–430°C for 2 h. The TeO2 (21 g, 84%) 
is cooled and bottled immediately to avoid slow darkening due to reduction by organic
matter from the atmosphere.
Te
conc. HNO3
2TeO2 . HNO3 400°C TeO2
TeCl4 + H2O TeOCl2 + 2HCl
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Tellurium dioxide is a white solid existing in two crystalline forms. It is soluble in water
and in both aqueous sodium hydroxide and hydrochloric acid. 
2.3 ALKALI METAL TELLURIDES (Te2!!Cat2"")These reagents are usually prepared in situ.
The preparative methods are outlined in sequence and representative experimental pro-
cedures are described in later chapters.
2.3.1 From the elements (2Na + Te →→ Na2Te)
2.3.1.1 In liquid ammonia4
2.3.1.2 In DMF5
2.3.1.3 In the presence of naphthalene6
2.3.2 From tellurium and reducing agents (Te →→ Te2−−)
2.3.2.1 Rongalite (HOCH2SO2Na/NaOH )7
2.3.2.2 Thiourea dioxide (TUDO, HN=C(NH2)S(O)OH)/NaOH8
2.3.2.3 Hydride transfer reagents
KBH4/NaOH9
Me4NBH4 (giving tetramethylammonium telluride)10
NaBH4/DMF11
NaBH4/H2O12
LiHBH313
2.3.2.4 Tin(II) chloride/KOH/DMSO14
2.3.2.5 Hydrazine hydrate/NaOH15
2.3.3 From tellurium and non-reducing bases
2.3.3.1 NaH/DMF16
2.3.3.2 NaH/DME17
2.3.3.3 NaH/N-methyl-2-pyrrolidone18
2.3 ALKALI METAL TELLURIDES (Te2!Cat2") 5
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2.4 ALKALI METAL DITELLURIDES (Na2Te2)
2.4.1 From the elements (2Na + 2Te →→ Na2Te2)
2.4.1.1 In liquid ammonia19
2.4.1.2 In HMPA20
2.4.1.3 In the presence of naphthalene21
2.4.2 From tellurium and reducing agents (2Te →→ Te22!!)
2.4.2.1 Rongalite22
2.4.2.2 TUDO/NaOH23
2.4.2.3 Hydride transfer reagents
NaBH4/EtONa/EtOH24
NaBH4/DMF25
2.4.2.4 Hydrazine hydrate/NaOH26
2.5 HYDROGEN TELLURIDE (H2Te)
Hydrogen telluride is prepared in situ by hydrolysis of aluminium telluride.27
Al2Te3 + 3H2O → 3TeH2 + Al203
2.6 SODIUM HYDROGEN TELLURIDE (NaHTe)
Sodium hydrogen telluride is prepared by reduction of tellurium with NaBH4 under sev-
eral conditions. The original procedure uses ethanol as the solvent, adding, after complete
reduction of the tellurium, an appropriate amount of acetic acid (see Section 4.1.2, ref. 10;
Section 4.1.7, ref. 29).
REFERENCES
1. Suttle, Y. F.; Smith, C. R. F. Inorg. Synth. 1956, III, 140.
2. Gerding, H.; Houtgraff, H. Recl. Trav. Chim. 1954, 73, 737.
3. Marshall, H. Inorg. Synth. 1950, III, 143.
4. Section 3.1.1.1 (a), ref. 1.
6 2. PREPARATION OF THE MORE IMPORTANT INORGANIC TELLURIUM REAGENTS
red
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5. Section 3.1.1.1 (a), ref. 8.
6. Section 3.1.1.1 (a), refs. 10, 11.
7. Section 3.1.1 1 (b), refs. 14, 15; Section 4.1.6, ref. 19; Section 4.1.9, ref. 33; Section 4.1.11, ref.
41; Section 4.2.5, ref. 6.
8. Section 3.1.1.1 (b), ref. 23.
9. Section 3.1.1.1 (b), ref. 24.
10. Section 3.1.1.1 (b), ref. 15.
11. Section 3.1.2.2, ref. 8; Section 4.1.11, ref. 40; Section 4.3.1.1, ref. 2.
12. Section 3.1.3.1, ref. 1; Section 4.1.13.1, ref. 49.
13. Section 5.1, ref. 2.
14. Section 3.1.1.1 (b), ref. 26.
15. Section 3.1.1.1 (b), ref. 27.
16. Section 3.1.2.1, ref. 5; Section 3.16.1.3, ref. 27; Section 4.1.5, ref. 17; Section 4.2.1, ref. 1;
Section 4.3.2.2, ref. 5.
17. Section 4.2.5, ref. 5.
18. Section 3.1.2.1, ref. 7.
19. Section 3.2.1.1, ref. 1.
20. Section 3.2.1.2, ref. 10.
21. Section 3.2.1.1, ref. 3.
22. Section 3.2.1.1, ref. 6.
23. Section 3.2.1.1, ref. 7.
24. Section 3.2.1.1, ref. 5.
25. Section 4.3.1.1, ref. 2.
26. Section 3.2.1.1, ref. 9.
27. Section 4.1.1.1, ref. 1; Section 4.1.4, ref. 14; Section 4.1.6, ref. 18.
REFERENCES 7
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– 3 –
Preparation of the Principal Classes of
Organic Tellurium Compounds
This chapter is devoted mainly to the preparation of those classes of organotellurium com-
pounds that have been more systematically investigated in past years, owing to their pecu-
liar role as reagents or intermediate in organic synthesis, including compounds of
structural, biological or theoretical interest.
Sections 3.1–3.3 outline the principal preparative methods of diorganyl tellurides and
ditellurides, organyltellurium trichlorides and diorganyltellurium dichlorides, which
were the first classes of compounds investigated at the beginning of tellurium organic
chemistry.
The physical properties and stability of the compounds are also described briefly.
DIORGANYL TELLURIDES (SECTION 3.1)
The main routes to symmetrical diorganyl tellurides involve the direct reaction of nucle-
ophilic telluride dianions (usually as Na2Te) with alkylating or arylating reagents.
Otherwise the electrophilic tellurium tetrahalides react with arylmagnesium reagents,
giving diaryl tellurides.
Unsymmetrical tellurides are obtained as follows:
• starting from nucleophilic tellurolate anions (easily generated by telluration of
Grignard and lithium reagents or by reduction of diorganyl ditellurides) by reaction
with alkylating or arylating reagents, or by addition to acetylenes;
• by cleavage of diaryl ditellurides with arylmagnesium reagents, diazonium salts, or
arenesulphonylazo compounds;
• by the reaction of electrophilic tellurenyl halides with Grignard reagents.
9
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10 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
Diorganyl tellurides have low molecular mass and are colourless or yellowish liquids with
an unpleasant and penetrating odour. Dimethyl telluride is a metabolite of tellurium and tel-
lurium compounds in a variety of living organisms, including humans. Higher dialkyl tellurides
and most diaryl tellurides are solids with low melting points (diphenyl telluride is a liquid).
Diorganyl tellurides are soluble in common organic solvents.
Because of the above-mentioned organoleptic properties, it is recommended that contact
between dialkyl tellurides and the skin is avoided, and that, in general, all work involving
diorganyl tellurides is performed under a well-ventilated hood.
The thermal stability and sensitivity to the atmosphere of diorganyl tellurides is dependent
on the organic moiety. Many aliphatic, cycloaliphatic, as well as vinylic and acetylenic tel-
lurides are reported to be decomposed by light, and therefore some authors recommend prepa-
ration of these compounds in the dark or under a red light.1 These tellurides are also sensitive
to exposure to the open atmosphere, easily undergoing oxidation to mixtures containing the
corresponding telluroxides in addition to other products. These oxidations are especially effec-
tive in solution, where the oxidation products separate as amorphous insoluble solids. Benzyl
groups in tellurides are characterized by a peculiar lability, as demonstrated by the oxidative
cleavage of aryl benzyl tellurides leading to aromatic carbonyl compounds.2 Diaryl tellurides
are generally more stable and can be handled in the open atmosphere.
DIORGANYL DITELLURIDES (SECTION 3.2)
Diorganyl ditellurides are prepared by three routes:
• alkylation or arylation of the ditelluride dianion (usually as Na2Te2);
• oxidation of tellurolate anions;
2ArX
ArTeAr
[2ArN2+]X-
Te2-
RTeR2RX
RX.R1X
ArMgX (exc.) TeX4
RTe- R
-
Te
R(Ar)R(Ar)Te
ArTeR RX ArTe- Ar
-
Te
NaBH4
Na (Li) ArTeTeAr
[ArTeX]
ArTeAr1
[Ar1N2+]X-
Ar1N = NSO2Ar
R-
Ar1-Ar1X
RTeR1 R
1X
X2
R(Ar)
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• reduction of the corresponding organyltellurium trichlorides.
The Te2 group is a chromophore, and aliphatic and aromatic ditellurides exhibit a char-
acteristic orange to pale or dark red colour (absorption maximum at ~400 nm).
The short-chain aliphatic ditellurides are liquids with a pungent odour, whereas the
higher members (more than 10 C chains) are solids with low melting points.
Diaryl ditellurides, which are more important as synthetic intermediates, are solids,
highly soluble in solvents such as petroleum ether, benzene, chloroform, ether, and tetrahy-
drofuran (THF), but are less soluble in methanol and ethanol.
Dibenzyl ditelluride exhibits the peculiar lability of the tellurium–benzyl bond already
mentioned for the corresponding tellurides. By heating the solid at 120°C, or by exposurein solution to ordinary incandescent lighting or to a Hanovia lamp, a rapid decomposition
into elementary tellurium and dibenzyl telluride occurs.3
ORGANYLTELLURIUM TRICHLORIDE AND DIORGANYLTELLURIUM
DIHALIDES (SECTIONS 3.5 AND 3.9)
Organyltellurium trichlorides and diorganyltellurium dichlorides are prepared starting
from the electrophilic tellurium tetrachloride (or aryltellurium trichlorides) by:
• condensation reactions with active methylene compounds;
• addition to a C!C bond (or a C!C bond, not shown in the scheme);
• electrophilic substitution in aromatic hydrocarbons; and
• reaction with organomercury chlorides.
Organyltellurium trichlorides and the not directly accessible tribromides and triiodides
are obtained by the halogenolysis of the Te–Te bond of the corresponding ditellurides.
Diorganyltellurium dihalides can also be prepared by the addition of halogens to the
parent tellurides.
TeCl4
R Y R Y
TeCl3
or
R
Y
)2 TeCl2
TeCl3
Cl
or
Cl
)2 TeCl2
ArTeCl3
ArHgCl
ArH ArH Ar2TeCl2
ArHgCl
Ar1HgCl ArAr1TeCl2
Te22-
RTeTeR
ArTeTeAr
RTeCl3
red.
ox. RTe-
red.
ox. ArTe-
ArTeCl3
Te
R-
Ar-
2RX
2ArX
ORGANYLTELLURIUM TRICHLORIDE AND DIORGANYLTELLURIUM DIHALIDES 11
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The tri- and dihalides are crystalline compounds. The chlorides are colourless (or yellow
such as some aryltellurium trichlorides), the colour changing to orange and red (or deep
red) for the bromides and iodides.
The aryltellurium trihalides are generally more stable than the alkyltellurium trihalides
(alkyltellurium trichlorides, produced by the addition of TeCl4 to olefins, easily liberate
elemental tellurium).
The reactivity of aryltellurium trihalides decreases on going from the chlorides to the
iodides, the same trend occurring for hydrolysis. Aryltellurium trichlorides are very sensi-
tive to water and moisture and are easily hydrolysed, the tribromides being more stable,
while the triiodides are unaffected by cold water and can be prepared even by aqueous pro-
cedures. Diaryltellurium dihalides are stable in water, and ionic exchange reactions allow
the conversion of dichlorides into dibromides and diiodides.
Aryltellurium trichlorides are highly soluble in methanol and ethanol but less soluble in
benzene. Diaryltellurium dichlorides exhibit inverse solubilities, being more soluble in
benzene than in methanol or ethanol. These properties allow an easy separation of diaryl
tellurides from diaryl ditellurides (frequently formed as by-products in the preparation of
tellurides): the mixture is treated with SO2Cl2 and the obtained mixed di- and trichlorides
are separated by the appropriate solvents, and reduced back into the pure tellurides and
ditellurides.
REFERENCES
1. Clive, D. L. J.; Chittattu, G. J.; Farina, V.; Kiel, W. A.; Menchen, S. M.; Russell, C. G.; Singh,
A.; Wong, C. K.; Curtis, N. J. J. Am. Chem. Soc. 1980, 102, 4438.
2. Ferreira, J. T. B.; Oliveira, A. R. M.; Comasseto, J. V. Tetrahedron Lett. 1992, 33, 915.
3. Spencer, H. K.; Cava, M. P. J. Org. Chem. 1977, 42, 2937.
ArTeTeAr
3X2 2ArTeX3
red X = Cl, Br, I
ArTeAr
X2 Ar2TeX2
red
ArTeCl3 ArAr1TeCl2
R Y R Y
ArTeCl2
Ar1H
Cl
ArTeCl2
12 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
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3.1 DIORGANYL TELLURIDES
Diorganyl tellurides, compounds with two organic groups linked to a tellurium atom,
constitute the most abundant and familiar class of organic tellurium compounds. The
organic groups, of the most differentiated types, can be identical or different, giving rise to
symmetrical or unsymmetrical tellurides.
Since symmetrical dialkyl and diaryl tellurides are the most employed in organic syn-
thesis, and often exhibit structural or biological interest, their preparation will be exam-
ined in detail, focusing on the methods and procedures that are considered as the most
popular.
3.1.1 Symmetrical dialkyl tellurides
3.1.1.1 From alkali tellurides and alkylating agents
Alkali tellurides, among which sodium telluride is the most widely employed, are power-
ful nucleophilic reagents and therefore react easily with alkylating agents.
(a) From sodium telluride prepared from the elements
(i) Sodium/liquid ammonia method
This method has been applied successfully to n- and s-alkyl halides.1–4
Dialkyl tellurides (general procedure).1 Elemental Te is added in ~0.5 g portions to a well-
stirred solution of Na in liquid NH3 until the solution decolourizes, forming a colourless
suspension (2 g-atom Na/1 g-atom Te). The quantities of the materials are chosen to give
a suspension of ~0.7 M. The alkylating agent is added dropwise in 10% excess to the 
suspension of Na2Te. The reaction mixture is stirred until the NH3 evaporates. H2O is then
added, the mixture extracted with ether and the ethereal solution worked up in the usual
manner.
Diethyltelluride: yield 80%; b.p. 38°C/14 torr, Diisopropyltelluride: yield 80%; 
b.p. 49°C/14 torr.
When the alkylating agent is insoluble in liquid ammonia, as in the case of long-chain
compounds, an organic solvent is added to the sodium telluride residue after evaporation
of the ammonia. Some cyclic and steroidal tellurides have been prepared from sodium tel-
luride in ethanol and the appropriate dihalides.5–7
Te + 2Na NH3 liquid Na2Te
RX RTeR
Te2- + 2RX RTeR
3.1 DIORGANYL TELLURIDES 13
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(ii) Sodium/DMF method 8,9
Bis(2-phenyl-1,2-dioxolan-2-yl)methyl telluride (R!Ph–C–CH2) (typical procedure).8
Finely powdered Te (0.30 g, 2.3 mmol) and Na (0.22 g, 9.6 mmol) are stirred under N2 in
dry DMF (15 mL) at 110°C until all the Te has disappeared (15 min). 2-(Bromomethyl)-
2-phenyl-1,3-dioxolane (1.15 g, 4.7 mmol) in dry THF (10 mL) is added to the resulting
yellowish suspension. After 2.5 h at room temperature the reaction mixture is poured into
H2O and extracted with ether. Chromatography on SiO2 (eluent: CH2Cl2/petroleum ether
at 40–60°C, 1:1) furnishes the telluride (0.65 g (60%); recrystallized from EtOH, m.p.
67–68°C).
Additional examples: R ! n-C12H25 (66%), PhCH!CH- (41%).9
(iii) Sodium/naphthalene method
Sodium telluride can be prepared under mild conditions from the elements in the presence
of catalytic amounts of naphthalene10 or by treating tellurium with sodium naphthalide.11
Dialkyl tellurides (general procedure).10 Te powder (3.58 g, 28 mmol), Na chips (1.29 g,
56 mmol), and naphthalene (0.72 g, 5.6 mmol) in THF (25 mL) are refluxed under N2 and
stirred for 3 h. The heterogeneous white mixture is cooled at 0°C and the alkyl halide 
(56 mmol) is added slowly, stirring for 30 min. After 30 min of additional stirring, the
mixture is filtered, the solution evaporated and the residue distilled under vacuum, giving
the telluride.
Diallyl telluride (typical procedure).11 In a 25 mL Schlenk flask, Te pieces (6.1 g, 48
mmol, from a Te ingot), Na (2.2 g, 96 mmol) and naphthalene (0.1 g, 0.8 mmol) in THF
(20 mL) are stirred under argon at 25°C for 4 days. The mixture is filtered and the filter
cake washed with THF (20 mL) and dried under vacuum to give Na2Te (7.6 g, 92%).
Alternatively, Te powder (60 mesh) and sodium naphthalide (2 mol equiv) are stirred in
THF for 4 h. Na2Te is isolated as an amber-coloured solid. The Na2Te (62.9 g, 0.362 mmol)
is slurried in absolute EtOH (400 mL). The slurry is cooled at 0°C and allyl bromide (93.3 g,
0.77 mmol) is added dropwise during a 1-h period while stirring. The mixture is stirred 
for an additional hour at 20°C and then filtered. The grey filter cake is washed with EtOH
(400 mL). The combined washing and filtrate are evaporated at atmospheric pressure. 
The residue is distilled, giving diallyl telluride as a pungent, air-sensitive, yellowliquid
(56.7 g (75%); b.p. 70–72°C/13 torr).
Te
Na/naphthalene
THF Na2Te
RX
(60-90%) RTeR
R = Et, n -Pr, n -Bu, MeOCH2CH2
Te + 2Na Na2Te
RX RTeRDMF
14 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
O O
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(b) From alkali tellurides prepared from tellurium and reducing agents
(i) Rongalite (sodium formaldehyde sulphoxylate) method
This method was first described at the beginning of the past century,12 and continues to
find a wide application.
n-Alkyl halides, benzyl chloride, ethyl sulphate, and s-alkyl bromides give 
the expected tellurides in medium yields whereas t-butyl chloride is not converted into the
telluride.13–15 Owing to the insolubility of the alkyl halides, ethanol must be added to 
the reaction mixture.
Dibenzyl telluride (typical procedure).15 Rongalite (18.0 g, 0.5 mol) is added under N2 at
80°C to a suspension of Te (2.56 g, 20 mmol) in a solution of NaOH (12 g, 0.3 mol) in 125
mL of H2O. After stirring for 1 h, a solution of benzyl chloride (1.26 g, 10 mmol) in a small
volume of EtOH is added dropwise at room temperature to the almost colourless telluride
solution. After stirring for an additional hour, the mixture is extracted with ether, and the
ethereal solution dried (MgSO4) and evaporated. The residue is recrystallized from petro-
leum ether (40–60°C) under red light, giving the telluride as yellow needles (1.09 g (70%);
m.p. 49–57°C).
Cyclic tellurides, 16–18 including some with a steroidal structure,19,20 have been prepared
by the Rongalite method.
(ii) Sodium dithionite and thiourea dioxide method
The use of sodium dithionite (Na2S2O4) and thiourea dioxide (TUDO; HN!C(NH2)S(O)OH)
has been introduced later as a reducing agent for the preparation of sodium telluride in an
aqueous medium, followed by reaction with n-alkyl halides to give dialkyl tellurides.21,22
The TUDO method has been reinvestigated and has found wide use because of the sim-
plicity of the experimental conditions.23
Te TUDO
NaOH/H2O/THF
Na2Te
RX
THF (CTBA)
(72-85%)
RTeR
R = n -C12H23, n -C8H17, i -C3H7CH2CH2, THPO(CH2)6
Te
( )n Y
Te Te
n = 1, 2
Y = 0, S
Te Na2Te
RX
RTeR
HOCH2SO2Na
NaOH/H2O
3.1 DIORGANYL TELLURIDES 15
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Dialkyl tellurides (general procedure).23 A mixture of TUDO (0.2 g, 2 mmol), NaOH
(0.112 g, 2.6 mmol), Te powder (0.128 g, 1 mmol) in H2O (0.75 mL) and THF (0.75 mL)
is refluxed for 1 h. The alkyl halide (2 mmol) and (cetyl trimethyl ammonium bromide)
CTBA (0.004 g, 1.1 ! 10"5 mmol) in THF (0.5 mL) are added to the pale pink solution.
After 1 h of additional reflux the mixture is worked up in the usual manner and the residue
purified by column chromatography on SiO2 (elution with petroleum ether 40–60°C).
(iii) Hydride transfer reagent method
A useful method for the reductive conversion of elemental tellurium into Te2" anions
employs complex hydrides such as sodium or potassium borohydride and tetraalkyl
ammonium borohydride as reducing agents.
Di-n-octyl telluride (typical procedure).24 Elemental Te (2.54 g, 20 mmol) is heated at reflux
in 20% aqueous NaOH (43 mL) containing KBH4 (2.7 g, 50 mmol), under argon. After 1.5
h the mixture is deep purple, but after an additional 30 min of reflux turns pale yellow and
no Te metal remains. Bromooctane (7.72 g, 40 mmol) in MeOH (50 mL) is added, the solu-
tion refluxed for 30 min, cooled, poured into H2O (100 mL) and extracted with ether (3!).
The ether extracts are washed with H2O, dried (Na2SO4) and evaporated. The oily residue is
distilled under vacuum, giving the telluride (5.5 g (78%); b.p. 154°C/0.7 torr).
Dibenzyl telluride (typical procedure).15 Elemental Te (1.27 g, 10 mmol) and Me4NBH4
(1.78 g, 20 mmol) are heated in H2O (100 mL) in a steam bath under N2 until the initially
produced purple colour is discharged. After cooling at room temperature, benzyl chloride
(2.53 g, 20 mmol) in EtOH (20 mL) is added slowly with stirring and rigorous exclusion
of air. After 2 h of stirring, the mixture is extracted with ether, dried and evaporated. The
residue is recrystallized from petroleum ether (under red light), giving the telluride as yel-
low needles (2.56 g (82%); m.p. 49–57°C).
In an interesting one-pot procedure the borohydride is used as both the reducing and
alkylating agent.25
Di-n-butyl telluride (typical procedure).25 Elemental Te (0.63 g, 5 mmol) and n-Bu4NBH4
(3.87 g, 15 mmol, 50% excess) are refluxed in toluene (80 mL) under N2 and stirring. The
initial red solution gradually turns colourless, giving a clear solution after 3 h. The cooled
solution is washed with H2O (50 mL) and 1 M HCl (50 mL) (evolution of H2). The organic
phase is dried (CaCl2) and evaporated, giving an oil (mixture of the telluride and
Bu3NBH3). The telluride is separated by column chromatography on SiO2 (eluent:
CH2Cl2/petroleum ether at 40–60°C, 1:1) (1.20 g (95%); nD20#1.5165).
Te + 2R4NBH4 RTeR + 2R3NBH3 + H2
Te RX RTeR
cat = Na+, K+, Me4N+
cat+BH4-
solvent/reflux Te
2-
16 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
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(iv) Tin(n)/potassium hydroxide method 26
Dimethyl telluride (typical procedure).26 KOH (100 g, 1.78 mol) in dimethyl sulfoxide
(DMSO) (180 mL) is heated on a steam bath. SnCl2 (10 g, 53 mmol) and Te powder 
(60 g, 0.47 mmol) are added and the mixture heated at 120°C for 20 h. After cooling at 40°C,
methyl iodide (157 g, 1.1 mol) is added dropwise for 2 h. The mixture is then heated at
70°C for 2 h and then distilled until the condensing vapour reaches a temperature of
100°C. The organic layer of the residue is separated, dried and distilled (71.6 g (97%);
b.p. 93–94°C).
(v) Hydrazine hydrate method 27
Dibutyl telluride (typical procedure).27 Hydrazine hydrate 80% (0.50 mL, 7.1 mmol) is
added dropwise using a syringe to a stirred mixture of finely ground Te (0.64 g, 5 mmol)
and powdered NaOH (0.40 g, 10 mmol) in DMF (10 mL) at 50–60°C. After 3 h stirring,
n-butyl bromide (1.4 g, 10 mmol) in DMF (2 mL) is added, the mixture is heated at 60°C
for a further 30 min, cooled at room temperature and extracted with petroleum ether
(40–60°C). The organic phase is separated, washed with H2O, dried (CaCl2) and evapo-
rated, giving the pure telluride (0.69 g (57%); b.p. 111–114°C/13 torr).
3.1.1.2 From bis(triphenylstannyl) telluride and alkylating reagents
The title reagent (prepared by the reaction of sodium hydrogen telluride with chlorotriph-
enylstannane)28 reacts easily with the more active halides such as benzyl bromides whereas
common halides need to be activated by cesium fluoride.29
Alkyl iodides and bromides react satisfactorily under these conditions whereas alkyl
chlorides and aryl halides are nonreactive.
RX = BzBr, n -C10H21I, n -C10H21Br, i -PrI, EtO2CCH2Br, PhCOCH2Br,
Cl(CH2)6Br (giving [Cl(CH2)6]2Te), Br
Br Tegiving
Ph3SnTeSnPh3 + RX
MeCN
THF PH3Sn TeSnPh3 R X
F..
-Ph3SnF
PH3Sn TeR R X
F..
40-100%
RTeR + Ph3SnF
Te Na2Te
RX
RTeR
DMF
N2H4/NaOH
(55-73%)
R = Et, n -Bu, n -pentyl, s -Bu, i -pr-CH2CH2, n -octyl
Te
SnCl2/KOH
DMSO, 120°C, 10h
K2Te
MeI MeTeMe
3.1 DIORGANYL TELLURIDES 17
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Dialkyl tellurides (general procedure).29 Bis(triphenylstannyl) telluride (1 equiv), alkyl
halide (2 equiv), excess CsF (4 equiv) and the solvent (MeCN or MeCN/THF) are mixed,
kept under N2 and monitored by thin layer chromatography (TLC) (or 1H NMR). Usual
work-up of the mixture yields the telluride.
REFERENCES
1. Brandsma, L.; Wijers, H. E. Recl. Trav. Chim. Pays-Bas 1963, 82, 68.
2. Sukhai, R. S.; Jong, R. A.; Verkruijsse, H. D.; Brandsma, L. Recl. J. R. Neth. Chem. Soc. 1981,
100, 368. Sukhai, R.S.; Jong, R. A.; Verkruijsse, H. D.; Brandsma, L. Chem. Abstr. 1982, 96,
104204.
3. US 2398414 (1946), Cal Research Corporation; Denison, G. H.; Condit, P. C. Chem. Abstr.
1946, 40, 3598.
4. Bogolyubov, G. M.; Shlyk, Y. N.; Petrov, A. A. J. Gen. Chem. USSR 1969, 39, 1768 (in English).
5. Buchta, E.; Greiner, K. Chem. Ber. 1961, 94, 1311.
6. Zanati, G.; Wolf, M. E. J. Med. Chem. 1972, 15, 368.
7. Zanati, G.; Gaare, G.; Wolf, M. E. J. Med. Chem.1974, 17, 561.
8. Engman, L. Organometallics 1986, 5, 427.
9. Ohe, K.; Takahashi, H.; Uemura, S.; Sugita, N. Nippon Kagaku Kaishi 1987, 1469.
10. Bhasin, K. K.; Gupta, V.; Gautam, A.; Sharma, R. P. Synth. Commun. 1990, 20, 2191.
11. Higa, K.; Harris, D. C. Organometallics 1989, 8, 1674.
12. Tschugaeff, L.; Chlopin, W. Ber. Dtsch. Chem. Ges. 1914, 47, 1274.
13. Balfe, M. D.; Nandi, K. M. J. Chem. Soc. 1941, 70.
14. Balfe, M. P.; Chaplin, C. A.; Phillips, H. J. Chem. Soc. 1938, 344.
15. Spencer, H. K.; Cava, M. P. J. Org. Chem. 1977, 42, 2937.
16. Farrar, W. V.; Gulland, J. M. J. Chem. Soc. 1945, 11.
17. McCullough, J. B. Inorg. Chem. 1965, 4, 862.
18. Holliman, F. G.; Mann, F. G. J. Chem. Soc. 1945, 37.
19. Knapp Jr., F. F. J. Labelled Compd. Radiopharm. 1980, 17, 81.
20. Suginome, H.; Yamada, S.; Wang, J. B. J. Org. Chem. 1990, 55, 2170.
21. Brigov, B. G.; Bregadze, V. I.; Golubinskaya, L. N.; Tonoyan, L. G.; Kozyzkin, B. I. USSR 541,
851, Chem. Abstr. 1977, 87, 5394.
22. Kozyzkin, B. I.; Salamtin, B. A.; Ivanov, L. L.; Kuzovlev, I. A.; Gribov, B. G.; Federov, V. A. Poluch.
Anal. Veshchestv Osoboi Chist [Dokl. Vses. Konf.] 1976, 5, 142, Chem. Abstr. 1979, 91, 140278.
23. Ferreira, J. T. B.; Oliveira, A. R.; Comasseto, J. V. Synth. Commun. 1989, 19, 239.
24. Kirsch, G.; Goodman, M. M.; Knapp Jr., F. F. Organometallics 1983, 2, 357.
25. Bergman, J.; Engman, C. Synthesis 1980, 569.
26. Voronkov, M. G.; Stankevich, V. K.; Rodkniko, P. A.; Korchevin, N. A.; Deryagina, E. N.;
Trofimov, B. A. J. Gen. Chem. USSR 1987, 57, 2398.
27. Lue, P.; Chen, B.; Yu, X.; Chen, J.; Zhou, X. Synth. Commun. 1986, 16, 1849.
28. Einstein, F. W.; Jones, C. H. W.; Jones T.; Sharma, R. D. Can. J. Chem. 1983, 61, 2611. 
29. Li, C. J.; Harpp, D. N. Tetrahedron Lett. 1990, 31, 6291.
3.1.2 Symmetrical diaryl tellurides
3.1.2.1 From sodium telluride and non-activated aryl halides
The normal low reactivity of aryl halides towards nucleophilic reagents is not generally
observed in their reaction with alkali tellurides. The observed reactivity seems to be
18 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
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dependent on the method employed to prepare the alkali telluride as well as on the experi-
mental conditions and solvents.
Non-activated aryl halides react only moderately with sodium telluride prepared from
the elements in inert solvents (DMF, N-methyl-2-pyrrolidone (NMP), hexamethylphos-
phoric acid triamide (HMPA)).1–4
Better results are achieved with tellurium and sodium hydride in DMF.5
Diaryl tellurides (general procedure).5 A mixture of powdered Te (0.128 g, 1.0 mmol), NaH
(0.053 g, 2.2 mmol, 60% suspension in oil, washed with hexane) and dry DMF 
(3 mL) is heated at 140°C for 1 h. Within 0.5 h the initial deep red colour is lost, and a 
pale yellow suspension is obtained. After cooling at room temperature, the aryl iodide 
(2.0 mmol) in dry DMF (3 mL) is added and the mixture heated at 130°C for 24 h. After
cooling at room temperature, the mixture is quenched with 10% aqueous NH4HSO4 (10 mL)
and extracted with ether (10 mL). The ethereal extract is washed with H2O, dried (Na2SO4)
and evaporated, giving the telluride, which is purified by column chromatography on SiO2
(eluent/hexane).
The Rongalite method (see Section 3.1.1.1b,i) can be successfully applied to the prepa-
ration of diaryl tellurides from aryl iodides.5,6 This method seems to be advantageous com-
pared to the preceding one because of the higher yields and milder experimental
conditions.
Some concurrent reactions sometimes observed in the above methods (dehydrohalo-
genation with the tellurium/Rongalite method and formation of tellurocarbamates
RTeC(O)NMe2 with the tellurium/NaH/DMF method) that decrease the yields of the
desired tellurides can be avoided by a modified procedure, where sodium telluride is gen-
erated by heating elemental tellurium and NaH in NMP.7 The deep purple solution of the
reagent prepared under these conditions can be stored for many days (in contrast to the use
Te
HOCH2SO2NA
NaOH/H2O
Na2Te
ArI
DMF, 60°C, 10 h
(55-94%)
ArTeAr
Ar = Ph and (alkyl and methoxy) derivatives, 1-naphthyl, 2-naphthyl
and derivatives, 9-anthryl, 9-phenanthryl, 1-pyrenyl
ArTeArTe NaH
DMF, 140°C
Na2Te
ArI
DMF, 130°C, 24 h
(41-70%)
Ar = 1-naphthyl and derivatives, 2- fluorenyl
Te + 2Na solvent Na2Te
ArX
solvent, 130-170°C, 16-24h
(35-50%)
ArTeAr
solvent = DMF, NMP, HMPA
ArX = PhI, 2-bromonaphthalene
3.1 DIORGANYL TELLURIDES 19
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of DMF as the solvent) without appreciable degradation.
Di(1-naphthyl) telluride (typical procedure).7 Finely ground Te (0.140 g, 1.1 mmol) and
NaH (2.2 mmol, 60% suspension in oil, washed with hexane) are heated in NMP (3.5 mL)
for 1 h. 1-Iodonaphthalene (0.310 g, 1.2 mmol) is added in small portions over 1.5 h to the
obtained solution of Na2Te at 100°C under argon. The resulting mixture is kept at this tem-
perature for 19 h. During this period the colour of the solution gradually changes from
deep purple to black. The progress of the reaction is monitored by TLC. After complete
disappearance of the starting material the reaction is quenched by addition of saturated
aqueous NH4Cl (1 mL) followed by benzene (5 mL). The Te deposit is filtered off and the
filtrate is partitioned between EtOAc (30 mL) and H2O (20 mL). The organic phase is
separated and dried (Na2SO4), the solvent is evaporated and the residue chromatographed
over SiO2 (eluent/hexane), giving the telluride. The product is recrystallized from hexane/
CHCl3 (1:1) as yellow crystals (0.160 g (76%); m.p. 123–126°C).
3.1.2.2 From sodium telluride or sodium O,O-diethyl phosphorotellurolate and
arenediazonium fluoroborates
Sodium telluride and sodium O,O-diethyl phosphorotellurolate, prepared respectively by
the Te/NaBH4DMF method and by the reaction of elemental tellurium with NaH and 
O,O-diethyl phosphate in ethanol, react with arenediazonium fluoroborates, giving good
yields of diaryl tellurides.8
Di(p-tolyl) telluride (typical procedure).8 Method A. Elemental Te (0.65 g, 5 mmol) and
NaBH4 (0.45 g, 12 mmol) in DMF (15 mL) are heated in a Schlenk reactor at 100°C with
stirring and under N2 until disappearance of the Te powder. The solution is cooled at 0°C and
p-toluenediazonium fluoroborate (2.06 g, 10 mmol) in DMF (5 mL) is added dropwise. The
mixture is stirred at 0°C for 30 min, quenched with H2O (20 mL) and then stirred continu-
ously for 30 min. The mixture is filtered, the filtrate extracted with ether (3!15 mL) and the
extracts washed with H2O (3!15 mL) and dried (MgSO4). The solvent is evaporated and the
residue recrystallized from MeOH, giving the telluride (1.05 g (68%); m.p. 67°C).
Method B. Elemental Te (0.64 g, 5 mmol), NaH (0.30 g, 10 mmol, 80% oil suspension,
washed with hexane) and (EtO)2P(O)H (1.41 g, 10 mmol, 97%) in anhydrous EtOH 
Te
(method A) NaBH4
DMF, 100°C
Na2Te
[ArN2+]BF4-
[ArN2+]BF4-
DMF, 0-5°C, 30min
(59-72%)
(method B)(EtO)2P(O)H (EtO)2P(O)TeNa
ArTeAr
DMF, r.t.
(64-94%)
NaH/EtOH, r.t. 
A = Ph and (alkyl, methoxy, halo and acyl) derivatives
NaH/NMP
100-110°C, 1 h
Te Na2Te
ArI
NMP, 50-110°C, 2-24 h
(42-77%)
ArTeAr
Ar = Ph and (alkyl and methoxy) derivatives, 1-naphthyl, 2-naphthyl,
1-(2-methyl)naphthyl
20 3. PREPARATION OF THE PRINCIPALCLASSES OF ORGANIC TELLURIUM 
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(20 mL) are stirred in a Schlenk apparatus at room temperature under N2 until disappear-
ance of the Te powder. p-Toluenediazonium fluoroborate (2.27 g, 11 mmol) in DMF 
(5 mL) is added slowly and the whole stirred for 30 min. The solution is diluted with H2O,
extracted with ether (3!15 mL) and the extract dried (MgSO4) and evaporated. The
residue is recrystallized from MeOH, giving the telluride (1.38 g (89%); m.p. 67°C).
3.1.2.3 From potassium tellurocyanate and arenediazonium fluoroborates
Another method that uses arenediazonium fluoroborates to prepare diaryl tellurides is the
reaction with potassium tellurocyanate.9 Aryl tellurocyanides are postulated as intermediates.
Diaryl tellurides (general procedure).9 Finely ground Te (1.6 g, 12.5 mmol) and KCN
(0.82 g, 12.5 mmol) in dry DMSO (20 mL) are heated at 100°C, for 1 h under N2. After
all the Te has dissolved, the mixture is cooled in an ice bath until most of the solvent has
solidified. The diazonium fluoroborate (12.5 mmol) is added rapidly while a brisk stream
of N2 is passed into the system. When the initial violent gas evolution has ceased, the ice
bath is removed and stirring is continued at room temperature for 3 h. The mixture is
diluted with CH2Cl2 (250 mL), filtered from the dark insoluble material (Te) and washed
several times with H2O. The solution is dried (CaCl2) and evaporated, giving an oil or a
pasty-solid, which is dissolved in CH2Cl2 and filtered through a short SiO2 column. (ln the
few cases where aryl tellurocyanides are formed as by-products, more careful chromato-
graphy is required with CH2Cl2/hexane, 1:1 as the eluent.)
The small amounts of diaryl ditellurides formed frequently as by-products can be con-
verted into tellurides by treatment with copper powder in refluxing dioxane.10 For
Ar"2HO2CC6H4, the crude product is extracted with aqueous Na2CO3 and precipitated
with acid (yield 8%).
3.1.2.4 From tellurium(IV) halides and arylmagnesium halides
In this method, the electrophilic tellurium tetrachloride is employed as starting material to
introduce tellurium in organic substrates, in contrast to the preceding methods using nucle-
ophilic tellurium species.
Tellurium tetrachloride (as well as tellurium tetrabromide and tellurium tetraiodide)
reacts with 4 mol equiv of arylmagnesium bromide, giving rise to diaryl tellurides in high
yields.11,12
TeX4 + 4ArMgBr
ether/benzene
0°C, reflux (>90%) ArTeAr + ArAr + 4MgBrX 
Ar = Ph; X = Cl, Br, I
Ar = 1-naphthyl, o -MeC6H4, p -MeC6H4; X = Br
2KTeCN + 2ArN2+]BF4- DMSO, r.t.
-N2, -2KBF4
[2ArTeCN]
(41-47%)
ArTeAr + Te(CN)2
Te + (CN)2
Ar = alkyl, methoxy, nitro, cyano, halophenyl derivatives, 2-biphenyl
3.1 DIORGANYL TELLURIDES 21
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The intermediates in these reactions are the corresponding triaryltelluronium halides
(which react with an additional equivalent of Grignard reagent) or the unstable tetraaryl-
tellurium derivatives.
This method is an efficient modification of the early method of Lederer,13 employing tel-
lurium dihalides (unstable compounds which disproportionate in elemental tellurium and
tellurium(IV) halides).
To make the isolation and purification of the products easier, the obtained tellurides are
converted in situ into the corresponding dichlorides, dibromides or diiodides by treating,
respectively, with sulphuryl chloride, bromine or iodine.11,12
Diphenyl telluride (typical procedure).12 To an ethereal solution of a Grignard reagent (100
mL), prepared from bromobenzene (39.3 g, 0.25 mol) and Mg (6.1 g, 0.25 mol), benzene
(100 mL) is added. The solution is cooled at 0°C and TeCl4 (13.5 g, 0.05 mol) in benzene
(200 mL) is added slowly with vigorous stirring. The reaction mixture is refluxed for 2 h,
then cooled at 0°C and quenched with saturated aqueous NH4Cl (300 mL). The organic
layer is separated, washed with H2O (3!), dried (Na2SO4) and evaporated in a rotatory
evaporator, giving the crude telluride. Treatment of the crude telluride with Br2 gives
diphenyltellurium dibromide (20 g (91%); m.p. 197°C).
3.1.2.5 From elemental tellurium and diarylmercury compounds
The reaction of diarylmercurials with elemental tellurium under heating, one of the oldest
methods for the preparation of diaryl tellurides,14–16 has been later employed in some spe-
cific cases.17–19
3.1.2.6 From diaryl ditellurides by extrusion of a tellurium atom
Diaryl ditellurides are relatively thermolabile compounds and eliminate one tellurium
atom by heating at ~300°C.20,21 In the presence of copper metal, however, the extrusion of
tellurium is achieved during reflux with toluene or dioxane.10,22–24
ArTeTeAr ~300°C
-Te
ArTeAr (Ar = Ph, p -MeOC6H4, p -EtOC6H4)
Cu
toluene, dioxane, reflux
(70-90%)
ArTeAr
Ar = p -MeC6H4, m -MeOC6H4, p -FC6H4, m -BrC6H4, p -NO2C6H4,
p -Me3SiC6H4, 4-biphenyl, [2-(2-quinolylphenyl)]
Ar2Hg + 2Te
>200°C
ArTeAr + TeHg
TeX4 + 3ArMgX
ArMgX
ArTeAr + ArAr
TeX4 + 4ArMgX [Ar4Te]
[Ar3Te+]X-
22 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
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Bis(2,4,6-trimethylphenyl) telluride (typical procedure).24 A solution of bis(2,4,
6-trimethylphenyl) ditelluride (4.94 g, 10 mmol) in toluene (150 mL) is refluxed in the
presence of electrolytic Cu (1.40 g, 22 mmol) for 12 h. The mixture is filtered and the 
filtrate evaporated to give the pure telluride (m.p. 123–125°C).
3.1.2.7 Bis-(phenylethynyl) telluride as Te2+ equivalent
On the basis that bis-organyl tellurides undergo Te/Li exchange by treatment with an
organolithium reagent, if a thermodynamically more stable organolithium moiety is
released,25 bis-(phenylethynyl) telluride26 has been employed as starting material for the
synthesis of diaryl tellurides.27
REFERENCES
1. Sandman, J. D.; Stark, J. C.; Acampora, L. A; Gagne, P. Organometallics 1983, 2, 549.
2. Sandman, D. J.; Stark; J. C.; Rubner, M.; Acampora, L. A.; Samuelson, L. A. Mol. Cryst. Liq.
Cryst. 1983, 93, 293.
3. Acampora, L. A.; Dugger, D. L.; Emma, T.; Mohammed, J.; Rubner, M. F.; Samuelson, L.;
Sandman, D. J.; Tripathy, S. K. Polym. Electron. 1984, 36, 461.
4. Sandman, D. L.; Stark, J. C.; Acampora, C. A.; Samuelson, C. A.; Allen, G. W. Mol. Cryst. Liq.
Cryst. 1984, 107, 1.
5. Suzuki, S.; Padmanabhan, S.; Inouye, M.; Ogawa, T. Synthesis 1989, 468.
6. Suzuki, H.; Inouye, M. Chem. Lett. 1985, 389.
7. Suzuki, H.; Nakamura, T. Synthesis 1992, 549.
8. Li, J.; Lue, P.; Zhan, X. Synthesis 1992, 281.
9. Engman, L. J. Org. Chem. 1983, 48, 2920.
10. Sadekov, T. D.; Bushkov, A. Y.; Minkin, V. T. J. Gen. Chem. USSR 1973, 43, 815.
11. Rheinboldt, H.; Petragnani, N. Chem. Ber. 1956, 89, 1270.
12. McWhinnie, W. R.; Patel, M. G. J. Chem. Soc. Dalton Trans. 1972, 199.
13. (a) Lederer, K. Bericht 1915, 48, 1345, 2049. (b) Lederer, K. Bericht 1916, 49, 334, 345, 1071,
1076, 2002, 2532, 2663. (c) Lederer, K. Bericht 1917, 50, 238. (d) Lederer, K. Ber. Dtsch. Chem.
Ges. 1919, 52, 1989. (e) Lederer, K. Bericht 1920, 53, 712.
14. Kraft, F.; Lyons, R. E. Bericht 1896, 27, 1769.
15. Zeiser, F. Bericht 1895, 28, 1760.
16. Lyons, R. E.; Bush, G. H. J. Am. Chem. Soc. 1908, 30, 834.
17. Hellwinkel, D.; Farbach, G. Tetrahedron Lett. 1965, 1823.
18. Cohen, S. C.; Reddy, M. L. N.; Massey, A. G. J. Organomet. Chem. 1968, 11, 563.
19. Jones, C. W. H.; Sharma, R. D.; Naumann, D. Can. J. Chem. 1986, 64, 987.
20. Farrar, W. V. Research 1951, 4, 177.
21. Petragnani, N.; Moura Campos, M. Chem. Ber. 1961, 94, 1759.
22. Haller, W. S.; Irgolic, K. J. J. Organomet. Chem. 1972, 38, 97.
2ArBr t -BuLi 2ArLi Ph CTeC Ph
-2PhC CLi
THF, -78°C
ArTeAr
(75-100%)
Ar = Ph, p -Me2NC6H4, p -MeOC6H4, p -HOC6H4, p -MeC6H4, m -MeC6H4,
o,m-Me2C6H3, o,p,o -Me3C6H2, 2 -thienyl,p -F3CC6H4, 2 -thianapftenyl
REFERENCES 23
Else_TOS-PETRAGNANI_Ch003.qxd 12/11/2006 3:58 PM Page 23
23. Sadekov, I. D.; Bushkov, A. Y.; Minkin, V. I. J. Gen. Chem. USSR 1977, 47, 576.
24. Akiba, M.; Lakshmikantham, M. V.; Jen, K. Y.; Cava, M. C. J. Org. Chem. 1984, 49, 4819.
25. Hiiro, T.; Kambe, N.; Ogawa, A.; Miyoshi, N.; Murai, S.; Sonoda, N. Angew. Chem. Int. Ed.
Engl. 1987, 26, 1187.
26. The synthesis of bis(phenylethynyl) telluride, isolated as the corresponding diiodide, was
described at first by Moura Campos, M.; Petragnani, N. Tetrahedron 1962, 18, 527. And later
by Dabdoub, M. J.; Comasseto, J. V.; Braga, A. L. Synth. Commun. 1988, 18, 1979. See Section
3.17.2.2.
27. Engman, L.; Stern, D. Organometallics 1993, 12, 1445.
3.1.3 Unsymmetrical tellurides
Unsymmetrical tellurides comprise a large class of organotellurium compounds character-
ized by two different alkyl groups, one alkyl and one aryl group, or two different aryl
groups linked to a tellurium atom. These compounds find only a minor use as reagents in
organic synthesis, but because of structural, and in some cases biological interest, their
preparation will be discussed in the following sections.
3.1.3.1 From sodium telluride and two different alkyl halides
Unsymmetrical telluro-substituted fatty esters (of biological interest) are obtained in about
40% yield after chromatographic separation from the symmetrical tellurides.1
n-Octyl (7-carbomethoxy)heptyl telluride (typical procedure).1 To a suspension of ele-
mental Te (0.127 g, 1 mmol) in H2O (3 mL) heated at 80°C is added a solution of
NaBH4 (0.100 g, 2.64 mmol) in H2O (1 mL), under red light, after careful deaeration
and argon purge. The obtained clear solution of Na2Te is cooled at room temperature
and a solution of methyl 8-bromooctanoate (0.223 g, 0.95 mmol) and 1-bromooctane
(0.202 g, 1.05 mmol) in THF/EtOH (1:1, 15 mL) is added under argon. The solution is
stirred for 1 h, poured into H2O (150 mL) and then extracted with ether (3!50 mL).
The ether extracts are washed with H2O (3!50 mL), dried (Na2SO4) and evaporated
under vacuum. The crude product is dissolved in petroleum ether (30–60°C) and puri-
fied by column chromatography on SiO2 slurried with petroleum ether (elution with
10!25 mL aliquots of petroleum ether followed by 10!25 mL aliquots of benzene,
monitoring the fractions by TLC). By combination of aliquots 13–16 the telluride is
obtained as an oil (0.155 g (39%)).
Te
NaBH4
H2O
Na2Te
(1) RX, (2) R1X
EtOH/THF
RTeR1 (+ RTeR + R1TeR1)
(25%) (25%)(25%)
R = n -Bu, n -octyl, p - IC6H4(CH2)9, CH C(CH2)3, CH(CH2)3
R1 = (CH2)nCO2Me
ICH
24 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
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Aryl alkyl tellurides are prepared in medium yields by sequential arylation/alkylation of
Na2Te generated by the described Te/NaH/NMP system (see Section 3.1.2.1).2
Methyl 2-naphthyl telluride (typical procedure).2 2-Iodonaphthalene (0.150 g, 0.59 mmol)
is added dropwise to a stirred solution of Na2Te (1.3 mmol) in NMP (4 mL) and the mix-
ture is heated at 120°C for 5 h. An excess of MeI (0.40 mL, 4.3 mmol) is then added and
the resulting mixture is stirred at 50°C for 2 h. Usual work-up gives the telluride as pale
yellow crystals (0.110 g (67%); m.p. 59–60°C).
3.1.3.2 From organyl tellurolates and alkylating agents
(a) From organyl tellurolates generated by tellurium insertion in organomagnesium or
organolithium reagents
The magnesium aryl tellurolates described earlier3 have seldom been employed for the
preparation of unsymmetrical tellurides.4–6
Elemental tellurium also inserts easily into a C(sp2)–Mg bond of a vinyl or styryl
Grignard reagent (see Section 3.16.1.4), but is unaffected by alkylmagnesium halides.7
In contrast, tellurium insertion in alkyl- or aryllithium compounds followed by alkyla-
tion is a useful method for the synthesis of unsymmetrical tellurides. (For a tabulation of
unsymmetrical tellurides prepared by alkylation of organyl tellurolates, see ref. 8.)
Methyl (3-hydroxy)propyl telluride (typical procedure).9 MeTeLi. A suspension of Te pow-
der (12.8 g, 0.1 mol) in THF (100 mL) is frozen in a liquid N2 bath, and then MeLi (66.7
mL of a 1.5 M solution in ether, 0.1 mol) is injected into the flask. The mixture is allowed
to thaw and is stirred magnetically for a further 30 min at room temperature. The resulting
yellow-orange solution is stored under N2 and used within 2 h.
MeTe(CH2)3OH. 3-Bromopropan-1-ol (6.95 g, 50 mmol) is injected into a frozen (by liquid
N2) solution of MeTeLi (50 mmol). The mixture is allowed to thaw and is stirred magneti-
cally at room temperature for about 1 h. Aqueous NaCl (100 mL) is then added and the
aqueous layer extracted several times with ether. The combined organic phases are dried
Te + RLi RTeLi R
1X RTeR1
Te + ArLi ArTeLi ArTeRRX
Te + ArMgBr ArTeMgBr RX ArTeR
Ar = Ph; R = Et, H2C-C
Ar = o-MeS-, o-Me2N, o-ClC6H4; R = Me (68-92%)
CH
Te NaH
NMP, 100-110°C, 1 h Na2Te
ArI (0.5 equiv)
NMP, 120°C, 2-4 h [ArTe
-] RX
NMP, 50°C, 2 h
(52-67%)
ArTeAr
Ar = o -MeC6H4, 1-naphthyl; R = n -hepthyl
Ar = 2-naphthyl; R = Me
3.1 DIORGANYL TELLURIDES 25
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(MgSO4) for 16 h, and evaporated. The residue is chromatographed on an SiO2 column (elu-
tion with petroleum ether 40–60°C), giving the telluride (8.3 g (83%)) in acceptable purity.
Methyl phenyl telluride (typical procedure).10 To a well-stirred suspension of Te powder
(3.0 g, 24 mmol) in anhydrous THF (36 mL) under argon is added dropwise an equimolar
amount of PhLi (1.5–2.0 M in ether). The mixture is then stirred for 2 h at room tempera-
ture, and for 1 h under reflux, and then MeI (3.4 g, 24 mmol) is added. After refluxing for
0.5 h the mixture is poured into three volumes of H2O, the aqueous layer is extracted with
CH2Cl2, and the combined organic phases are washed with H2O, dried (Na2SO4) and evap-
orated. The oily brown residue is distilled under vacuum, giving the telluride (2.1 g (43%);
b.p. 57–58°C/0.7 torr).
(b) From organyl tellurolates generated by the cleavage of ditellurides with alkali metals
or reducing agents
The reductive fission of diaryl ditellurides with sodium in liquid ammonia reported ear-
lier11 has seldom been employed.12,13 More recently, aprotic solvents have been substituted
for ammonia.14–16
A practical and successful method employs lithium in THF.17
Alkyl phenyl tellurides (general procedure).17 Li metal (1.4 g, 0.2 mol) in small pieces is
added under N2 to a solution of diphenyl ditelluride (4.1 g, 10 mmol) in dry THF (100 mL).
The mixture is stirred at room temperature for 6 h, unreacted lithium is removed using a
spatula and the alkyl halide (20 mmol) neat or in THF is added dropwise to the stirred
yellowish-brown solution. The solution is stirred at room temperature for 30 min, and under
reflux for an additional 30 min. The solvent is evaporated, and H2O (10 mL) and ether 
(25 mL) are added to the residue, mixing thoroughly. The ethereal phase is separated and
evaporated. The residue is fractionally distilled under vacuum (yields 62–79%).
Actually, the method of choice for the preparation of organyl tellurolate anions is the
reduction of diorganyl ditellurides with reducing agents.
NaBH4 is the more widely used reagent owing to the mild experimental conditions. The
choice of solvent, or solvent mixture, and of neutral or basic media is governed by the fur-
ther use of the tellurolate solution. Typical media are benzene/ethanol/aqueous NaOH,18
MeOH or EtOH.19–21
Medium-to-high yields of the expected tellurides are obtained from diaryl or dialkyl
ditellurides and n- and s-alkyl halides (and steroidal tosylates).
ArTeTeAr (RTeTeR) NaBH4
EtOH (MeOH) ArTeNa (RTeNa)
R1X
ArTeR1 (RTeR1)
ArTeTeAr LiTHF
ArTeLi RX ArTeR
Ar = Ph; R = Me, Et, n -Pr, n -Bu, n -C14H29 (62-84%)
R = i -prop (46%)
26 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
Else_TOS-PETRAGNANI_Ch003.qxd 12/11/2006 3:58 PM Page 26
Reactions with epoxides are also successful, giving the corresponding hydroxy tel-
lurides.19
Phenyl dodecyl telluride (typical procedure).19 To a solution of diphenyl ditelluride
(1.21 g, 2.96 mmol) in absolute EtOH (100 mL) is slowly added powdered NaBH4
(0.23 g, 6.08 mmol) under N2 at room temperature. At the end of the addition the 
red colour is discharged and 1-bromododecane (1.5 g, 6.02 mmol) is added by a
syringe. The mixture is refluxed for 3.5 h (during this period the progress of the reac-
tion is monitored by TLC; the plates are developed in the dark) and then evaporated.
The residue is purified by chromatography on SiO2 (eluting with CCl4), giving the tel-
luride (1.73 g (76%)).
Diaryl ditellurides, like diaryl disulphides and diselenides,22 undergo disproportionation
into arene tellurolates and tellurinates by alkaline treatment.
The tellurolate anion formed can be alkylated in situ, giving alkyl aryl tellurides, if the
above reaction is effected in the presence of a phase transfer catalyst.23 Otherwise, per-
forming the reaction in the presence of the reducing agent TUDO a telluride yield near 
to quantitative is generated, owing to the reduction of the aryl tellurinate anion to aryl 
tellurolate.24
Alkyl aryl tellurides (general procedure).24 To a solution of diaryl ditelluride (1.0 mmol)
in THF (7.5 mL) are added TUDO (0.108 g, 1.0 mmol), 2HT (0.030 g) and the alkyl halide
(2.0 mmol). Then, 50% NaOH (7.5 mL) is added and the mixture is stirred vigorously for
several hours at room temperature. The phases are separated, and the organic phase is
extracted with EtOAc (3!20 mL). The combined organic phases are washed with H2O,
dried (MgSO4) and evaporated. The residue is purified by column chromatography on SiO2
(eluting with EtOAc).
Aryl ditellurides are cleaved by samarium diiodide (SmI2) to generate the new nucleo-
philic species diiodosamarium aryl tellurolate which reacts smoothly with alkyl and acyl
ArTe- + RX (81-96%)
ArTeR
Ar = Ph, 2-naphthyl, p -MeOC6H4, m-F3CC6H4
R = n- and s-alkyl, benzyl
2ArTeTeAr + 4OH- 3ArTe- + ArTeO2- + 2H2OPTC
TUDO
2ArTeTeAr + 4OH- 3ArTe- + ArTeO2- + 2H2O
ArTeNa + O
R
R
R
R
OHArTe
3.1 DIORGANYL TELLURIDES 27
Else_TOS-PETRAGNANI_Ch003.qxd 12/11/2006 3:58 PM Page 27
halides, and even with aryl halides to afford the corresponding tellurides and tel-
luroesters.25–27
Reaction of diphenyl ditelluride with organic halides mediated by SmI2.25 Samarium
powder (0.20 g, 1.3 mmol) was placed in a well-dried, two-neck, round-bottom flask con-
taining a magnetic stirrer bar. The flask was flushed with nitrogen several times.
Methylene diiodide (0.32 g, 1.2 mmol) in THF (7 mL) was added through a rubber sep-
tum by a syringe. The mixture was stirred at room temperature until the solution became
deep green and homogeneous (0.5–1 h). HMPA (0.7 mL) was then added and the solu-
tion became deep purple; the THF-HMPA solution of SmI2 was ready for subsequent use.
To the THF-HMPA (7–0.7 mL) solution of SmI2 (1.2 mmol), prepared as described
above, was added a mixture of ditelluride (0.21 g, 0.5 mmol) and organic halide (1 mmol)
in THF (7 mL) at room temperature, and the solution was stirred for 5 h, during which time
its colour changed into brownish-yellow. The reaction solution was poured into diluted
HCl, and the mixture was extracted with ether (2!15 mL). The ethereal solution was
treated with aqueous Na2S2O3, washed with brine, and dried (MgSO4). Evaporation of the
solvent left a yellow oil that was subjected to preparative TLC on silica gel (petroleum
ether as eluent), giving the phenylalkyl tellurides.
Diisobutylaluminium benzenetellurolate, generated in situ from diphenyl ditelluride and
diisobutylaluminium (DIBAL), reacts with acetals, alkyl sulphonates and oxiranes, giving
the expected tellurides in high yields.28
OMs
( )11
same condition TePh
( )11
(46%)
C6H13OMs(OTs) same condition C6H13TePh
(72%)
RCH(OMe)2
(i-Bu)2AlTePh
CH2Cl2
r.t.
reflux
C11H23CH
TePh
TePh
RCH OMeTePh
(42-80%)
(50%)
R = H, C11H23
ArTeTeAr + 2SmI2 THF/HMPA
r.t., 0.5 h, 1 h
2 "ArTeSmI2"
RX
r.t., THF, 3 h
ArTeR
RCOCl
r.t., 2 h
ArTeCOR
(77, 72%)
Ar = Ph, p -MeC6H4
R = Ph
Ar = Ph, p -MeC6H4
X = Cl, Br
Y = CN, CO2Et
Ar = Ph
X = Br, I
R = Me, Et, prop, n -Bu
i -propyl, PhCH2
C
H
ArTe C
Y
CN
(64-85%)
C
H
X C
Y
CN
THF, r.t., 3h
28 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
Else_TOS-PETRAGNANI_Ch003.qxd 12/11/2006 3:58 PM Page 28
(c) From organyl telluroesters generated by the reduction of organyltellurium 
trichlorides with NaBH4
The reaction of organyltellurium trichlorides with NaBH4 followed by the in situ treatment
of the generated tellurolate with alkyl halides is a useful method to prepare several types
of unsymmetrical telluride.29
Transformation of aryltellurium trichlorides into alkyl aryl tellurides (typical proce-
dure).29 To a solution of the aryltellurium trichloride (5 mmol) and the appropriate alkyl
halide (7.5 mmol) in THF (60 mL) under a nitrogen atmosphere, was slowly added a solu-
tion of NaBH4 (0.93 g, 25 mmol) in water (30 mL) at 0°C. The colour changed from 
yellow to red when the addition of NaBH4 started and to yellow again after the addition
was completed. After the addition, the mixture was stirred for 20 min at room temperature
and then treated with saturated aqueous solution of NH4Cl (100 mL) and extracted with
ethyl acetate (3!20 mL). The extracts were washed with brine (3!20 mL) dried with
MgSO4 and the solvents were evaporated. The residue was purified by column chro-
matography on silica gel, eluting with hexane, to give the aryl–alkyl tellurides.
Vinylic30 and cyclic organyltellurium trichlorides31 undergo similar reactions.
n = 1
R, R1, R2 = H
R = i -prop; R1, R2 = Me
n = 2 R, R1, R2 = H
OR TeCl3
R1
R2
( )n 1) NaBH4
THF/H2O
2) n-BuBr OR
TeBu-n
R1
R2
( )n
(90-95%)
R
Cl
R1
TeCl3
1) NaBH4
THF/H2O
2) EtBr/N2
R
Cl
R1
TeEt
R = Ph; R1 = Ph, Me
(78, 75%)
ArTeCl3
NaBH4
THF/H2O
0°C
ArTeNa RX
THF/N2
ArTeR
(88-95%)
Ar = Ph, p -MeOC6H4, p -C6H5OC6H4
RX = MeI, EtBr, Me(CH2)2CH(Me)Br
same conditionO( )n
n = 4, 10
OH
TePh( )
(80%)
n
same conditionO
R
OH
RCHCH2TePh
R = Me, Et, C12H25
(70-88%)
3.1 DIORGANYL TELLURIDES 29
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3.1.3.3 By addition of aryl tellurolates to electrophilic alkenes
Aryl tellurolates add to alkenes bearing electron-withdrawing groups in a typical 1,4-Michael
addition, giving !-telluro-substituted derivative.32
3.1.3.4 From organyl tellurolates and arylating agents
The arylation of organyl tellurolates, restricted first to aryl halides activated by electron-
withdrawing groups,24 or requiring special conditions such as heating in HMPA in the
presence of CuI,33 or photostimulation in liquid ammonia,12,13 has later been achieved suc-
cessfully with non-activated aryl halides under normal conditions.6
Methyl o-methoxyphenyl telluride (typical procedure).6 To a frozen solution of MeTeLi (50
mmol) is added o-bromoanisole (9.3 g, 50 mmol). The mixture is allowed to warm at room
temperature, stirred for 1.5 h and then quenched with deoxygenated H2O (100 mL). The
organic product is extracted with ether (3!50 mL), the organic extracts dried (MgSO4) for
16 h and evaporated, and the residue is distilled under vacuum, giving the telluride as a
pale yellow oil (9.3 g (74%)).
Arenediazonium salts34,35 as well as arenesulphonylazo compounds36 have also found a
use as arylatingagents for arene tellurolates.
PhTeLi + ArN = NSO2C6H4CH3
18-crown-6
MeCN, r.t. PhTeAr
ArTeTeAr
NaBH4
EtOH/THF/NaOH aq.
ArTeNa
[Ar1N2+]X- ArTeAr1
RLi + Te RTeLi ArX RTeAr (R = Me, Ph) (ref. 6)
PhTeTePh PhTeArPhTeNa
Na/NH3 ArX
UV
(ref. 12,13)
PhTeTePh
1) NaBH4/HMPA, 70-80°C
2) CuI, 3) ArI (80-90%) PhTeAr
Ar = nitroaryl
[ref. 33]
Te + RLi THF
r.t., N2
[RTeLi] EtOH
r.t.
R1
R2
EWG
[RTeH] EWGR1
RTe
R2
R = Bu, s -Bu
EWG = CN, CHO, COR, CO2R
R1, R2 = H
R1 = H; R2 = Me, cyclohexenone, 4,4-dimethyl cyclohexenone
(98%)
R
Y
PhTeNa/EtOH
(PhTe)2/NaBH4(31-71%)
PhTe
Y
R
R = H, Me; Y = CO2Et, CN
30 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
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Reaction of diarylditellurides with arenediazonium salts (typical procedure). p-Methoxy
phenyl p-tolyl telluride.35 With heating and stirring in an atmosphere of nitrogen, sodium
tetrahydroborate was added in small portions to a solution of 9.4 g of bis(p-methoxyphenyl)
ditelluride in a mixture of 50 mL of ethanol and 15 mL of benzene until the solution was
decolourized completely (1.5 g was required). Then 8.24 g of p-toluenediazonium fluo-
roborate was added rapidly and the mixture was stirred for 1 h and poured into dilute HCl.
The oil formed was extracted with ether, and the extract was washed with water and dried
over CaCl2. Ether was evaporated, and the residue was dissolved in benzene and chro-
matographed on alumina (eluent hexane). After the evaporation of hexane, 4.8 g (36%) of
the telluride was isolated, m.p. 64–64.5°C (hexane).
Trimethylsylilmethyl telluride generated in situ from methyllithium and trimethyl-
chlorosilane can be used instead of the tellurolate in the latter reaction.36
3.1.3.5 From diorganyl ditellurides or arenetellurenyl halides and organometallic
reagents
A different approach to unsymmetrical diorganyl tellurides, in which an electrophilic tel-
lurium species is used, involves the nucleophilic attack of organomagnesium or organo-
lithium reagents to diorganyl ditellurides.
Only half of the tellurium of the starting ditelluride is converted into telluride. The other
half, converted into tellurolate, can be oxidatively recovered as the starting ditelluride.
If the diaryl ditelluride is previously converted in situ into the corresponding tellurenyl
halide, both the electrophilic tellurium moieties are used.41 (The stable crystalline 2-naph-
thyltellurenyl iodide42 (see Section 3.7) reacts similarly.) The reaction is of general appli-
cation, giving high yields of the expected tellurides with aromatic, aliphatic, cycloaliphatic,
vinylic43 and acetylenic Grignard reagents,44 under mild conditions.
Unsymmetrical diorganyl tellurides (general procedure).41 A solution of the ditelluride 
(2 mmol) in THF (30 mL) is treated dropwise at 0°C under N2 with Br2 (0.32 g, 3 mmol)
ArTeTeAr
THF/benzene
X2 [ArTeX] RMgX(>90%) ArTeR
Ar = Ph, p -Me, p -MeO, p -EtOC6H4
R = Ph, n -Bu, cyclohexyl, PhC C ; X = Br, I
RTeTeR R1Met RTeR1 + RTeMet
R R1 Met
aryl
aryl, alkyl
alkyl
aryl
alkyl
alkyl
MgX, Li
MgX, Li
Li
(ref. 37, 39)
(ref. 39, 40)
(ref. 38, 6)
+
MeTeLi + Me3SiCl MeTeSiMe3
ArN = NSO2C6H4CH3 MeTeAr
3.1 DIORGANYL TELLURIDES 31
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in benzene (4 mL). The Grignard reagent is then added dropwise by means of a syringe.
Gradual disappearance of the red colour of the solution is observed. Finally, the solution
becomes almost colourless after the addition of a 10% excess of the Grignard reagent.
After stirring for 30 min at room temperature the solution is diluted with petroleum ether
30–60 C (30 mL) and treated successively with aqueous NH4Cl and brine. The organic
layer is dried (MgSO4) and evaporated, giving the telluride.
3.1.3.6 Additional methods
(a) From dialkyl ditellurides and arenediazonium fIuoroborates45
(b) From diaryl ditellurides and dialkylmercury reagents46,47
(c) From phenyl tellurocyanate and alcohols48
(d ) From diphenyl ditellurides and trialkyl boranes49
PhTeTePh RTePh
R3B
O2/THF (64-95%)
Selected examples:
R = n -C6H13, n -C16H33, c-hex, Br(CH2)5,
PhCH2OCO(CH2)4
R3B = n -C6H13B(c-hex)2
PhTeTePh
1) NaBH4
2) BrCN PhTeCN
ROH
Bu3P/CH2Cl2
PhTeR
R = n -C8H17, n -C11H23, n -C12H25, n -C14H29, n -C16H33,
Ph(CH2)2, Ph(CH2)3, n -C12H25CHCH3
(41-78%)
ArTeTeAr + R2Hg
dioxane/reflux
-Hg (70-80%) 2 ArTeR
Ar = Ph
R = n -C4H9, i -C4H9, Bz
RTeTeR ArTeR
[ArN2+]BF4-
CHCl3(CH2Cl2), KOAc,
18-crown-6
(25-48%)
R = Et
Ar = 2-halC6H4, 2-MeC6H4, 3-MeC6H4, 4-MeC6H4,
2-AcC6H4, 2-CO2HC6H4 
32 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
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(e) From trimethylsylilphenyl tellurium and organyl halides50
( f ) From arylethynyl tellurides and aryllithium
The protocol shown in Section 3.1.2.7 is also useful to prepare unsymmetrical diaryl 
tellurides.51
(g) From aryltellurium tribromides and arylboronic acids52
(h) From diaryl ditellurides and ethyldiazoacetate53
REFERENCES
1. Goodman, M. M.; Knapp Jr., F. F. Organometallics 1983, 2, 1106.
2. Suzuki, H.; Nakamura, T. Synthesis 1992, 549.
3. Giua, M.; Cherchi, F. Gazz. Chim. It. 1920, 50, 362.
4. Bowden, K.; Braude, A. E. J. Chem. Soc. 1952, 1076.
5. Pourcelot, G.; Lequan, M.; Simmonin, M. P.; Cadiot, P. Bull. Soc. Chim. Fr. 1962, 1278.
6. Kemmitt, T.; Levanson, W. Organometallics 1989, 8, 1303.
7. Haller, W. S.; Irgolic, K. J. J. Organomet. Chem. 1972, 38, 97.
8. Irgolic, K. J. in Houben-Weyl-Methods of Organic Chemistry. 4th edn, Vol. E12b, p. 389. Georg
Thieme, Stuttgart, 1990.
PhTeTePh N2CHCO2Et PhTeCH2CO2Et
(70%)CuSO4, benzene
reflux
ArB(OH)2 + Ar1TeBr3 MeNO2
reflux, 30min
Ar Te Ar1
Br Br
NaHSO3 ArTeAr1
(46-54%)
Ar = o -NO2C6H4, m -NO2C6H4
Ar1 = m, m -Me2C6H3
ArTe-C Ph + Ar1Li THF
-78°C ArTeAr
1 + PhC CLi
(44-85%)
Ar = p -Me2NC6H4, p -MeOC6H4
Ar1 = Ph, p -MeOC6H4, p -MeC6H4, p -FC6H4, p -F3CC6H4
Me3SiTePh + RX MeCN RTePh + Me3SiX(60-100%)
X = Br
R = sec -C10H21, PhCH2, o -ClC6H4CH2, m -ClC6H4CH2, ,
allyl, cinnamyl, c-hex, t -But (36%), (48%),
Ph CH2 CH2
N N
N
N
REFERENCES 33
Else_TOS-PETRAGNANI_Ch003.qxd 12/11/2006 3:58 PM Page 33
9. Hope, E. G.; Kemmitt, T.; Levanson, W. Organometallics 1988, 7, 78. 
10. Seebach, D.; Beck, A. K. Chem. Ber. 1975, 108, 314.
11. Lederer, K. Ber. Dtsch. Chem. Ges. 1915, 48, 1345; see also Liesk, J.; Schultz, P.; Klar, G. Z.
Anorg. AlIg. Chem. 1977, 435, 98.
12. Pierini, A. B.; Rossi, R. A. J. Organomet. Chem. 1979, 168, 163.
13. Pierini, A. B.; Rossi, R. A. J. Org. Chem. 1979, 44, 4667.
14. Uemura, S.; Fukuzawa, S. I.; Yamauchi, T.; Hattori, K.; Mizutaki, S.; Tamaki, K. J. Chem. Soc.
Chem. Commun. 1984, 426.
15. Engman, L. Organometallics 1986, 5, 427.
16. Ohe, K.; Takahashi, H.; Uemura, S.; Sugita, N. J. Organomet. Chem. 1987, 326, 35.
17. Irgolic, K. J.; Busse, P. J.; Grigsby, R. A.; Smith, M. R. J. Organomet. Chem. 1975, 88, 175.
18. Piette, J. L.; Renson, M. Bull. Soc. Chim. Belg. 1970, 79, 353.
19. Clive, D. L.; Chittattu, G. J.; Farina, V.; Kiel, W. A.; Menchen, S. M.; Russel, C. G.; Sing, A.;
Wong, C. K.; Curtis, N. J. J. Am. Chem. Soc. 1980, 102, 4438.
20. Knapp, F. F.; Ambrose, K. R.; Callahan, A. P. J. Med. Chem. 1981, 24, 794.
21. Uemura, S.; Fukuzawa, S. J. Am. Chem. Soc. 1983, 105, 2748.
22. Rheinboldt, H. in Houben-Weyl-Methoden der Organischen Chemie (ed. E. Muller). 4th edn,
Vol. IX, p. 1102. Georg Thieme, Stuttgart, 1955.
23. Comasseto, J. V.; Ferreira, J. T. B.; Fontanellas, J. A. J. Organomet. Chem. 1984, 277, 261.
24. Comasseto, J. V.; Lang, E. S.; Ferreira, J. T. B.; Simonelli F.; Correia, V. R. J. Organomet. Chem.
1987, 334, 329.
25. Fukuzawa, S. I.; Niimoto, Y.; Fujinami,T.; Sakai, S. Heteroatom. Chem. 1990, 1, 491.
26. Zhang, Y.; Yu, Y.; Lin, R. Synth. Commun. 1993, 23, 189.
27. Bao, W.; Zhang, Y. Synth. Commun. 1995, 25, 1913.
28. Sasaki, K.; Mori, T.; Doi, Y.; Kawachi, A.; Aso, Y.; Otsubo, T.; Ogura, F. Chem. Lett. 1991, 415.
29. Chieffi, A.; Menezes, P. H.; Comasseto, J. V. Organometallics 1997, 16, 809.
30. See Section 3.16.2.1.
31. See Section 4.5.1.1.
32. (a) Ohe, K.; Takahashi, H.; Uemura, S.; Sugita, M. Nippon Kagaku Kaishi 1987, 1469. (b) Zinn,
F. K.; Righi, V. E.; Luque, S. C.; Formiga, H. B.; Comasseto, J. V. Tetrahedron Lett. 2002, 43,
1625.
33. Suzuki, H.; Abe, H.; Ohmasa, N.; Osuka, A. Chem. Lett. 1981, 1115.
34. Piette, L.; Thibaut, P.; Renson, M. Tetrahedron 1978, 34, 655.
35. Sadekov, J. D.; Ladatko, A. A.; Minkin, U. I. J. Gen. Chem. USSR 1977, 47, 2194.
36. Evers, M. J.; Christiaens, L. E.; Renson, M. J. J. Org. Chem. 1986, 51, 5196.
37. Petragnani, N. Chem. Ber. 1963, 86, 247.
38. Herberhold, M.; Leitner, P. J. Organomet. Chem. 1987, 336, 153.
39. O!Brien, D. H.; Dereu, N., Huang, C. K.; Irgolic, K. J.; Knapp, F. F. Organometallics 1983, 2,
305.
40. Dereu, N.; Piette, I. L. Bull. Soc. Chem. Fr. 1979, 623.
41. Petragnani, N.; Torres, L.; Wynne. K. J. J. Organomet. Chem. 1975, 92, 185.
42. Vicentini, G. ; Giesbrecht E.; Pitombo, L. R. M. Chem. Ber. 1959, 92,40.
43. Dadboub, M.; Dabdoub, V. M.; Comasseto, J. V.; Petragnani, N. J. Organomet. Chem. 1986,
308, 211.
44. Moura Campos, M.; Petragnani, N. Tetrahedron 1982, 18, 527.
45. Luxen, A.; Christiaens, L. Tetrahedron Lett. 1982, 3905.
46. Okamoto, Y.; Yano, T. J. Organomet. Chem. 1971, 29, 99.
47. Vychkova, T. I.; Kalabin, G. A.; Kushnarev, D. F. J. Org. Chem. Russia 1982, 17, 1179.
48. Ogura, F.; Yamaguchi, H.; Otsubo, T.; Chikamatsu, K. Synth. Commun. 1982, 12, 131.
34 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
Else_TOS-PETRAGNANI_Ch003.qxd 12/11/2006 3:58 PM Page 34
49. Abe, T., Aso, Y.; Otsubo, T.; Ogura, F. Chem. Lett. 1990, 1671.
50. Yamago, S.; Lida, K.; Yoshida, J. I. Tetrahedron Lett. 2001, 42, 5061.
51. Engman, L.; Stern, D. Organometallics 1993, 12, 1445.
52. Clark, A. R.; Nair, R.; Fronczek, F. R.; Junk, T. Tetrahedron Lett. 2002, 43, 1387.
53. Dabdoub, M.; Guerrero, P. G.; Silveira, C. C. J. Organomet. Chem. 1993, 460, 31.
3.1.4 Diorganyl tellurides by reduction of diorganyltellurium dihalides
Diorganyltellurium dihalides are often the primary products in the synthesis of organic
derivatives of tellurium and are therefore immediate precursors of the corresponding 
tellurides.
The most employed reducing agents in the “old” tellurium chemistry were alkali sul-
phites or hydrogen sulphites, methylmagnesium iodide and sodium sulphide hydrate. The
last reagent is still used, together with the more recently introduced sodium borohydride,
TUDO, hydrazine, samarium diiodide and sodium ascorbate.1
Often the sequence
is employed for isolation and purification purposes, since the dihalides are generally
solid, easily recrystallizable compounds, and the two steps cause only a little loss in the
telluride yield.
Reduction of diorganyltellurium dihalides
With sodium sulphide hydrate (general procedure).2 The diorganyltellurium dihalide is
mixed with a 15 times molar excess of Na2S·9H2O and the mixture heated at 95–100°C for
10 min or more, until all the solid has melted. Sufficient H2O is added to dissolve the sul-
phide and then the mixture is filtered if the obtained telluride is a solid, or extracted with
a solvent (ether or petroleum ether) if the telluride is a liquid. The products are purified by
crystallization or distillation. Yields are high or quantitative (except for diphenyl telluride
or di-p-tolyl telluride).
With sodium borohydride – tetrahydrotellurophene (typical procedure.3 NaBH4 is added to
a boiling methanolic solution of diiodotetrahydrotellurophene until the orange colour dis-
appears. The solution is filtered and the filtrate is poured into H2O (1 L). Extraction with
ether, followed by drying (CaCl2) and evaporation, gives the product as a yellow oil with
a persistent odour (b.p. 165–167°C/760 mmHg; no yield was given).
With TUDO (general procedure).4 A mixture of diorganyltellurium dihalide (2 mmol) and
2 N NaOH (10 mL) is stirred at room temperature for 15 min. TUDO (0.432 g, 4 mmol)
R2Te
X2 R2TeX2
red R2Te
RTeR red RTeR
X X
REFERENCES 35
Else_TOS-PETRAGNANI_Ch003.qxd 12/11/2006 3:58 PM Page 35
and petroleum ether (30–60°C, 10 mL) are then added and the two-phase system is stirred
at room temperature until the mixture turns clear. The phases are separated and the aqueous
phase is extracted with ether (3!). The combined organic phases are dried (MgSO4) and the
solvent is evaporated. The residue is placed on an SiO2 column and eluted with petroleum
ether giving the telluride (dibutyl, didodecyl, butyl phenyl, and di-4-methoxyphenyl tel-
luride; yields 77–90%).
With hydrazine – di-p-anisyl telluride (typical procedure).5 p-Anisyltellurium dichloride
(8.3 g, 0.02 mol) suspended in EtOH/H2O (150:15) is heated under reflux, and hydrazine
(3.2 g, 0.1 mol) is added dropwise (vigorous evolution of N2). When further addition of
hydrazine no longer causes evolution of N2, the mixture is poured into H2O (700 mL), and
extracted with ether (2!300 mL). The extracts are washed with H2O, dried and evapo-
rated, giving the telluride. The product is recrystallized from MeOH (at "25°C) (5.2 g
(77%); m.p. 57°C).
3.1.5 Additional methods
Sodium ascorbate6 and samarium diiodide7 have also been used as reducing agents.
Reduction of diaryltellurium dichlorides with sodium ascorbate (typical procedure).6 Bis
(p-methoxyphenyl)tellurium dichloride (0.20 g, 0.48 mmol) dissolved in acetone (10 mL)
was added to a stirred solution of sodium ascorbate (0.20 g, 1.0 mmol) in water/methanol
(2#8 mL). After 24 h, water (50 mL) and CH2Cl2 (50 mL) were added and the two phases
separated. The organic phase was dried (CaCl2) and the solvent evaporated in vacuo. Flash
chromatography yielded 0.14 g (84%) of bis(p-methoxyphenyl) telluride.
Reduction of diaryltellurium dichlorides with samarium diiodide (typical procedure).7
Diaryl tellurium dichloride (1 mmol) was added to the deep blue solution of SmI2 (2.2
mmol) in THF (22 mL) at room temperature under nitrogen with stirring. The deep blue
colour of the solution disappeared immediately and became yellow. The resulting solution
was stirred at room temperature under nitrogen for 30 min. To the solution was added
dilute hydrochloric acid, and the mixture was extracted with ether. The ethereal solution
was washed with brine and dried over MgSO4. The solvent was evaporated in vacuo, and
the residue was purified by preparative TLC on silica gel (petroleum ether–methylene
dichloride as eluent).
REFERENCES
1. For an extensive coverage on the reduction of diorganyltellurium dichloride see: Rheinboldt, H.
in Houben-Weyl-Methoden der Organishen Chemie (ed. E. Muller). 4th edn, Vol. IX, p. 1068.
Georg Thieme, Stuttgart, 1955. Irgolic, K. J. in Houben-Weyl-Methods of Organic Chemistry.
4th edn, Vol. El2b, p. 426. Georg Thieme, Stuttgart, 1990.
2. Reichel L.; Kirschbaum, E. Chem. Ber. 1943, 76, 1105.
3. AI-Rubaie, A. Z.; Alshirayda, H. A. Y. J. Organomet. Chem. 1985, 287, 321.
36 3. PREPARATION OF THE PRINCIPAL CLASSES OF ORGANIC TELLURIUM 
Else_TOS-PETRAGNANI_Ch003.qxd 12/11/2006 3:58 PM Page 36
4. Lang, E. S.; Comasseto, J. V. Synth. Commun. 1988, 18, 301.
5. Bergman, J. Tetrahedron 1972, 28, 3323.
6. Engman, L.; Persson, J. Synth. Commun. 1993, 23, 445.
7. Jia, X.; Jin, P.; Zhang, Y.; Zhou, X. Synth. Commun. 1995, 25, 253.
3.2 DIORGANYL DITELLURIDES
Three main routes have been well established for the preparation of diorganyl ditellurides:
(1) The reaction of sodium ditelluride with alkylating or arylating agents.
(2) The oxidation of tellurols or